Ameriglo fits an increasing need - Ameriglo Pro I-Dot Tritium Night Sight Set - S&W M&P, ProGlo Green Front w/ Orange Outline & Single Dot Green Rear

Originally, I would have said something along the lines of: "For aging eyes"....HOWEVER, the need to clearly focus on the front sight, along with the night vision scenario (no longer a theory....rather a real possibility...real scenario)....the highly-visible orange front sight dot, couple with the tritium module, has evolved into a "standard" of sorts, for home defense and self defense pistols.
Ameriglo products are the most affordable sets in this field. I highly recommend them. Have had ZERO issues with the several I have installed...